JP2641343B2 - Drive unit for thermal printer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal printer capable of performing a printing process in either a state in which an ink ribbon is mounted on a carriage having a thermal head or a state in which thermal paper is used without mounting an ink ribbon. In a printer, the present invention relates to a driving device for moving the carriage.

[0002]

2. Description of the Related Art Generally, a thermal printer includes a carriage movable in a printing direction and a return direction, and a thermal head to which a printing pattern is applied is provided on the carriage. A cassette-shaped ink ribbon is detachably attached to the carriage, and when the ink ribbon is mounted, printing is performed by transferring the ink of the ink ribbon to a sheet. When the ink ribbon is not mounted, printing is performed by using thermal paper. The printing process is performed when the carriage is moved in the printing direction. At this time, a printing pattern is applied to the thermal head. When printing of one line is completed, the carriage is moved in the return direction, and then moved again in the printing direction.
By repeating this, printing of one page is performed.

As a driving motor for moving the carriage in the printing direction and the return direction, a motor having a high moving accuracy such as a pulse motor is generally used.

[0004]

In recent years, however, there has been an increasing demand for high-speed printer devices, and it has become an essential element to increase the operation speed other than during the printing operation. Therefore, it is conceivable to increase the speed by increasing the return speed of the carriage, but it is necessary to provide an inexpensive printer. In view of this cost, the motor for driving the carriage is designed so that the torque becomes a necessary minimum value. Therefore, the carriage cannot be pulled at high speed with the ink ribbon cassette attached. Therefore, conventionally, the return speed of the carriage has been low.

An object of the present invention is to provide a driving device for a thermal printer capable of increasing the speed of the printer as a whole by speeding up only the operations that can be performed using a motor having a required minimum torque. It is in.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a thermal printer having a carriage which is moved in a printing direction and a return direction in a state where an ink ribbon is mounted or not, and a method for mounting the ink ribbon on the carriage. A detector for detecting the presence / absence of the ink ribbon; means for returning the carriage at a first speed when the presence of the ink ribbon is detected by the detector; Means for returning the carriage at a second speed higher than the speed.

[0007]

When a motor having a minimum necessary torque for pulling at a printing speed is used with the ink ribbon mounted as a motor for pulling the carriage, the carriage is slow when the ink ribbon is mounted on the carriage. Returned at speed. However, when the ink ribbon is not mounted on the carriage, the load due to the ink ribbon is eliminated, so that the carriage can be moved at high speed even with a motor having a low torque.
According to the present invention, when the absence of the ink ribbon is detected, the carriage is returned at the high second speed, whereby the carriage can be quickly returned to the home position.

[0008]

FIG. 1 is a view showing a carriage portion of a thermal printer according to an embodiment of the present invention.

A carriage 1 can mount a cassette-shaped ink ribbon (not shown), and a thermal head 2 is provided upright on the back side in the figure. A micro switch SW is arranged on the upper surface of the carriage 1. The micro switch SW detects the mounting state of the ink ribbon. A home position sensor HPS (not shown) is provided on the bottom surface of the carriage, and detects the home position of the carriage. At the time of printing processing, a printing pattern is applied to the surface of the thermal head 2 (the back side in the figure) and pressed against the platen 3. When printing is performed using the ink ribbon, a sheet is disposed between the platen 3 and the thermal head 2, and the ink ribbon is hung on the front side of the thermal head 2.
The print pattern is applied to the surface of the thermal head 2 to transfer the ink of the character pattern onto the paper. During printing using thermal paper, the platen 3
The thermal paper is disposed between the thermal paper and the thermal head 2, and when the thermal head 2 is pressed against the thermal paper surface, the thermal paper is heated and colored in a character pattern.

A shaft 4 is disposed below the carriage 1, and the carriage 1 is slidably mounted on the shaft 4. A belt 5 is fixed to the carriage 1. The belt 5 is endless and is stretched between rollers. Roller on which the belt 5 is stretched (not shown)
Is connected to a pulse motor, and rotates the belt 5 one step at a time. With this configuration, the carriage 1 is pulled by the belt 5 and is moved along the shaft 4 in the direction of arrow F (printing direction) or the direction of arrow R (return direction) by one step.

FIG. 2 is a block diagram of a control unit of the thermal printer. CPU1 controls the entire thermal printer
1 is performed. The ROM 12 stores a program for controlling each part of the thermal printer. RAM
13 stores data and the like necessary for this control. The ROM 12 further includes a carriage print speed pattern (print motor table), a return speed pattern when the ink ribbon is mounted (return motor table), and a return speed when the ink ribbon is not mounted (high speed return). Motor table) is stored.

This data can be stored in a RAM backed up by a battery.

Here, the normal return speed and the high return speed will be described. As a motor for moving the carriage 1, a motor which waits for a minimum torque necessary for moving the carriage with the ink ribbon attached thereto at a printing speed is used for cost reduction. For this reason, if an attempt is made to increase the return speed with the ink ribbon attached, the load is too large, and the motor cannot rotate, causing troubles such as burning. Therefore, when the ink ribbon is mounted, the return is performed at a low speed, and a motor table for normal return that stores the pattern is provided. On the other hand, when the ink ribbon cassette is not mounted, even if the carriage motor is rotated at a high speed,
Since the load is small, the moving speed of the carriage sufficiently follows. Therefore, a high-speed return motor table storing the high-speed movement pattern is provided.

Various sensors such as a micro switch SW for detecting the attachment / detachment of the ink ribbon, a home position sensor HPS for detecting the home position of the carriage, input keys for print processing, and an input unit are input to the CPU 11. A host or the like that transmits data is connected. As the output unit, a head driver for controlling the print pattern of the thermal head, a motor driver for controlling the moving speed of the carriage, and the like are connected. C
The PU 11 outputs a print pattern of the thermal head to the head driver based on the input data, and outputs a motor drive pattern for moving the carriage to the motor driver.

5 is a flowchart showing a processing procedure at the time of printing processing in the thermal printer configured as described above.

When the printing process is started, a printing pattern is applied to the thermal head and data based on the printing motor table is given to the motor driver. As a result, the carriage 1 moves at a predetermined printing speed in the direction of arrow F, and a one-line printing operation is performed (n1 → n).
2). When the printing process of one line is completed, whether or not the ink ribbon is attached or detached is read, and the return speed of the carriage is set according to the state (n3 → n4, n5). That is, when the SW is on (the state where the ink ribbon is mounted), the normal return motor table is read to drive the motor (n4 → n6), and the SW is off (the state where the ink ribbon is not mounted). Reads the high-speed return motor table and drives the motor (n5
→ n6). Thereby, when the ink ribbon is not mounted, the return speed is increased, and the processing speed can be increased. In this way, the carriage 1 returns and returns to the home position HPS, and the above processing is repeated until the printing processing is completed (n7 → n8).

In the above embodiment, the return speed is set by creating a table. However, it is also possible to set the return speed by incorporating a function into a program.

[0018]

According to the present invention, the processing speed can be increased as much as possible by using an inexpensive motor with a low output torque without using a motor with a large torque. In other words, the return speed of the carriage is set to be slow when the ink ribbon is attached to the carriage and the carriage moving load is large, but the return speed of the carriage is set to be fast when the ink ribbon is not attached to the carriage and the carriage moving load is small. Thus, the overall processing speed is increased while enabling the use of a motor having a low output torque.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a carriage portion of a thermal printer.

FIG. 2 is a block diagram of a control unit of the thermal printer.

FIG. 3 is a flowchart showing a processing procedure during printing processing of the thermal printer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Carriage 2 Thermal head 3 Platen 4 Shaft 5 Belt SW Micro switch

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-78765 (JP, A) JP-A-60-30369 (JP, A) JP-A-1-168458 (JP, A)

Claims (1)

(57) [Claims] 1. A thermal printer comprising a carriage which is moved in a printing direction and a return direction in a state where an ink ribbon is mounted or not mounted, a detector which detects whether or not the ink ribbon is mounted on the carriage. Means for returning the carriage at a first speed when the presence of the ink ribbon is detected by the detector; and a second speed higher than the first speed when the absence of the ink ribbon is detected by the detector. Means for returning the carriage by means of: a driving device for a thermal printer.